Abstract
Background
Metastatic uveal melanoma (mUM) is associated with poor prognosis. Treatment with ipilimumab/nivolumab has shown antitumor efficacy. Tebentafusp resulted in longer overall survival (OS) compared to investigator`s choice in a phase III study. The aim of this study is to describe the radiological response patterns with both treatments in association with the treatment outcome.
Methods
Patients with mUM treated with ipilimumab/nivolumab or tebentafusp with available radiological assessment per RECISTv1.1 and/or imPERCIST5. Disease outcome, landmark progression-free survival (PFS) and OS were reported. The same criteria were used to assess the liver-specific response.
Results
14 patients were treated with ipilimumab/nivolumab; treatment efficacy for best overall response (BOR) per RECIST v1.1 and imPERCIST5 was similar for the PFS (p=0.37 and p=0.23) and OS (p=0.14 and p=0.23). Patients with complete metabolic response (CMR), partial metabolic response (PMR) and partial response (PR) had longer PFS by trend. Treatment efficacy at the liver was concordant with the overall treatment efficacy for the PFS and OS.
22 patients were treated with tebentafusp; BOR per imPERCIST5 and RECISTv1.1 did not differ for the PFS (p=0.48 and p=0.21, respectively) and OS (p=0.63 and p=0.32, respectively). The hepatic treatment efficacy was concordant with the overall treatment efficacy. Patients with liver SD as best response showed a significant OS benefit (p=0.045).
Conclusion
Comprehensive radiological response evaluation with both RECIST v1.1 and imPERCIST5 can synergistically provide with an accurate assessment of immunotherapy efficacy in mUM, but both methods display limitations. Further studies to investigate the mechanisms of response and resistance are required.